Stroboscopic watch timer



CROSS KR shag-7M3? Oct. 17, 1967 E. J. PAss STROBQSCOPIC WATCH TIMER Filed Aug. 17, 1964 Inventor EDWIN .1. PASS by: Qmmgflamm.

United States Patent O 3,347,086 STROBOSCOPIC WATCH TIMER Edwin John Pass, 118 Grant Ave., Hamilton, Ontario, Canada Filed Aug. 17, 1964, Ser. No. 390,045 1 Claim. (Cl. 73--6) ABSTRACT OF THE DISCLOSURE An apparatus for indicating the accuracy of balance wheel operated time pieces as an aid in their adjustment. A synchronous motor operated from commercial power lines drives a cam operated switch to fix the cycling rate of a stroboscope. The cam can be changed to accommodate a variety of time pieces. A special lens system and a polarizing viewer to reduce glare are also disclosed.

The invention relates to a stroboscopic device for timing and regulating watches and the like.

The timing or regulating of watches and the like by stroboscopic means has been proposed in various ways. One of the more promising methods proposed has been by directing a stroboscopic flashing light on the balance wheel of the watch and adjusting the regulator of the watch until the balance wheel was observed to 'be apparently stationary. When this condition existed, the balance wheel was thought to be in synchronism with the stroboscopic light and therefore perfectly regulated. However, such a system has met with a number of practical difliculties, and, for example, the problem of providing an exact reference timing for the stroboscopic light corresponding precisely to the correct timing of the balance wheel has never been satisfactorily overcome. Thus, one such prior proposal has utilized a second watch movement connected to an electrical contact breaker for providing the timing of the stroboscopic light. Obviously, such mechanical methods introduce substantial errors such that watches timed by such a system will always be timed to a relatively low degree of accuracy, and the reference watch movement will require rechecking almost daily on some other timing or regulating mechanism. A further and more serious problem has been encountered in the optical viewing of the balance wheel itself. Watch movements are commonly polished to a high degree of mirror finish such that a stroboscopic light placed within a few inches of the watch movement and flashing at a rate of perhaps 300 flashes a minute will dazzle the eye of the operator and render it impossible for him to see the balance wheel at all in the brief interval between flashes.

Furthermore, a flashing rate of 300 per second as has.

been used in the past places severe limits on the life of the bulb.

Accordingly, it is an objective of the present invention to provide a stroboscopic watch timing device having a very high degree of accuracy of reference timing and incorporating a viewer which is effective to eliminate flashing reflections of the stroboscopic light and enabling the operator to observe the balance wheel unhindered.

More particularly, it is an objective of the present invention to provide a stroboscopic watch timing device having the foregoing advantages which is operated directly off the domestic power line and timed by synchronous means controlled by the domestic power line cycle.

More particularly, it is an objective of the present invention to provide a stroboscopic Watch timer having the foregoing advantages which incorporates an optical viewer having adjustable means permitting the operator to increase or decrease the percentage of light reaching his eye from the watch movement.

3,347,686 Patented Oct. 17, 1967 "ice More particularly, it is an objective of the present invention to provide a stroboscopic watch timing device having the foregoing advantages which is simple and economical to manufacture and highly reliable in use and incorporates a readily interchangeable means for adjusting the reference timing of the device for different makes of watch movements.

A preferred embodiment of the invention will now be described with reference to the following views and diagrams in which like reference devices refer to like parts thereof throughout the various views and diagrams and in which:

FIGURE 1 is a schematic perspective illustration showing the method of operation of the device;

FIGURE 2 is a circuit diagram of the stroboscopic light portion of the device;

FIGURE 3 is a sectional side elevation of the lamp and lamp-holder of the device; and

FIGURE 4 is a sectional side elevation of a portion of the optical viewer.

With reference first of all to FIGURE 2, it will be noted that the stroboscopic light system according to the invention comprises the mercury vapour tube 10 operable to provide a stroboscopic flashing light and of known design and manufacture, which is powered by condenser 11 which is in turn charged through silicon rectifier 12 which is in turn connected to the domestic power supply through transformer 13, fuse 14, on/off switch 15, and plug 16. Mercury tube 10 is provided with the magnetic coil 17 wound therearound which is in turn energized through transformer 18 by means of battery power source 13 and contact breaker 29 which is intermittently operable to provide a rapid rise and decay of voltage in the primary winding of transformer 18 to procure, through the secondary winding thereof, intermittent energizing of magnetic coil 17. Contact breaker 20 is itself operated in precisely timed synchronism with the cycle rate of the domestic power supply by means of synchronous electric motor 21 and the specially designed cam 22 which is mounted on shaft 23 thereof. Cam 22 is removable from shaft 23 and may be replaced by a cam of different design having a different number of lobes 22a thereon for providing a different reference timing. In operation, plug 16 is inserted into a power supply socket and immediately electrical motor 21 will begin to operate causing a regular precisely timed cyclical make and break of contact breaker 20 in precise synchronism with the cycling rate of the domestic power supply. Such make and break at contact breaker 20 will procure intermittent energizing of magnetic coil 17 around mercury tube 10 which is itself of known design such that it becomes conducting in the presence of an inductive electromagnetic field and becomes non-conductive when such field is cut off. When it is desired to establish a stroboscopic flashing light, switch 15 is closed thus applying the domestic power supply to transformer 13. The transformer output is subject to half wave rectification by rectifier 12 and then charges up one side of condenser 11. On each occasion that mercury tube 10 is rendered conducting in the manner aforesaid, a high energy discharge of condenser 11 will take place through tube 10 thus providing a brilliant precisely timed flash on each occasion, in precise synchronism with the cycle time ic light having a repetition rate of three hundred flashes per minute can be produced and will provide a precise and unvarying timing for such a watch movement. In the case of certain more expensive watch movements the balance wheel system is designed to cycle at seven cycles per second or four hundred and twenty cycles per minute and an alternative cam 22 having a greater number of lobes 22a will sufiice to provide such higher flashing rate.

While an operation of this nature, producing a flashing rate of either 300 per second or 420 per second will provide efficient and accurate regulating of a watch movement of the appropriate type, it has been found according to the invention that such a high flashing rate results in severe limitations on the life of mercury tube 10. In addition, a flashing rate equal to the cycling rate of the balance wheel will result in the balance wheel being viewed at both ends of its cycle, or two other points in the cycle spaced apart by the same distance. While this is apparently a desirable characteristic, it has been found in practice, according to the invention, that if the balance wheel will be viewed only at one end of its swing, the human eye is much more readily capable of detecting slight differences in location of a predetermined point on the balance wheel and as a result, the watch movement can be regulated much more quickly. Accordingly, while a flashing rate corresponding to the designed cycling rate of the balance wheel will provide adequate regulation in most instances, it is greatly to be preferred to provide a flashing rate equal to an even fraction, such as /2, A and the like of the designed cycling rate of the balance wheel in order to take into account the limited accommodation of the human eye. In addition, the reduced flashing rate will greatly prolong the life of mercury tube and increase the reliability and serviceability of the apparatus.

Turning now to FIGURE 1 and FIGURE 4, it will be noted that according to this preferred embodiment of the invention, the balance wheel is viewed through an optical viewer 24 similar in design to the conventional watchmakers eye glass which is preferably provided with a conventional magnifying lens 25 and two superimposed glass filters 26 and 27. Filters 26 and 27 are of Polaroid glass design and filter 26 is fastened in fixed relation Within viewer 24. Filter 27 however is movably mounted in track 28 for rotational movement and is provided with the finger stud 29 for operation thereof. In this way, the operator can observe the balance wheel of the watch and rotate filter 27 by means of stud 29 to increase or decrease the amount of light passing through filters 26 and 27. In this way, the operator can adjust the amount of light reaching his eye to counteract the degree of reflectivity on any particular watch movement under observation.

From FIGURE 3 it will be noted that mercury tube 10 is mounted in a cylindrical container 30 somewhat similar to a flashlight in design, having at one end a lens 31 of Lucite (the trademark of Dupont Company of Canada) or like acrylic plastic, having suitable optical characteristics to procure a concentrated pencil-like beam of light which can be accurately directed on a watch movement. Lens 31 is provided with a greatly enlarged base 32 for collecting the maximum amount of light within container 30.

Also mounted within container 30 is the transformer 18 in order to provide leads 33 of minimum length connecting the secondary winding of transformer 18 to magnetic coil 17. Transformer 18 and tube 10 are preferably mounted on a baseboard 34 which may also carry leads 35 for connection of the tube '10 to the power source as shown in FIGURE 2. Screw-on cap 36 is provided for container 30 to permit removal of the tube 10 for replacement and servicing when necessary and container 30 is also provided with ribs 37 for giving a secure grip to an operation.

The foregoing .is a description of a preferred embodiment of the invention by way of example only and the invention comprehends all such changes as come within the spirit and scope of the following claim.

What I claim is:

In apparatus for testing the timing of watch movements, a stroboscope comprising: a mercury vapour tube adapted to be connected to an alternating current power source; a rectifier between said tube and power source; a magnetic coil about said tube which, when energized causes said tube to be energized; said coil being included in a circuit; a battery powering said circuit, contacts controlling the completion of said circuit; a synchronous motor adapted to be connected to said power source and having a drive shaft, a cam removably and drivably mounted on said shaft and operatively connected to said contacts; a lens associated with said tube for concentrating light therefrom into a pencil beam adapted to be directed onto the balance wheel of a watch being tested; and an optical viewer including a light polarizing filter for viewing the balance wheel with the beam directed thereon.

References Cited UNITED STATES PATENTS 2,064,812 12/1936 Bouchard 88-65 X 2,096,696 10/1937 Land 88-65 2,183,655 12/1939 Morton 736 2,712,231 7/ 1955 Frolow 73--6 3,004,191 10/1961 Umbarger 315241 LOUIS R. PRINCE, Primary Examiner. DAVID SCHONBERG, Examiner.

S. C. SWISHER, Assistant Examiner, 

